Switching apparatus



Oct# 22, 1940. H. sENGEBUscH SWITCHING APPARATUS Filed June 20, 1938 5 Sheets-Sheet l l L -l+ Il WNMQ Q EQ m. im

IN VENT OR.

HAN S SENGEBUSCH BY .QV l.

AWORNEYS.

Oct. 22, 1940. H. SENGEBUSCH 2,218,834

SWITCHING APPARATUS Filed June 20, 1938 5 Sheets-Sheet 2 slum m I/v /1 /1 INVENTOR.

HAN S SENGEBUSCH BY/oam, ATTORNEYS,

Oct. 22, 1940. H SENGEBUSCH 2,218,834

SWITCHING APPARATUS Filed June 20, 1958 5 Sheets-'Sheet 3 INVENTOR. HAN S SENGEBU SCH ATTORNEYS.

Oct. 22, 1940. H SENGEBUSCH 2,218,834

SWITCHING APPARATUS Filed June 20, 1938 '5 Sheets-Sheet 4 @dos 43 M3@ INVENTOR. HAN S SENGEBUSCH ATTORNEYS,

oct. 22, .1940. H SENGEBUSCH 2,218,834

SWITCHING APPARATUS FIC-.#9 0 Flcflo INVENTOR. HANS SENGEBUSCH BY M,M,M gr/MQ ATTORNEY5.

Patented Oct. 22, 1940 UNITED STATES SWITCHING APPARATUS Hans s engebusch, Villa Park, Ill., assignor to Associated Electric Laboratories, Inc., Chicago,

Ill., a corporation of Application June 20,

31 Claims.

The present invention relates to switching apparatus and more particularly to improvements in switching apparatus of the form suitable for use in automatic telephone exchanges.

As pointed out in the copending application of Hans Sengebusch, Serial No. 214,721, filed June 20, 1938, disclosing and claiming switching apparatus of this character, one of the major items of cost in an automatic telephone exchange, both in the installation and in the maintenance thereof, is the multiples extending between the bank contacts of the various automatic switches. Switching apparatus, comprising a. plurality of automatic switching units and an associated conductor bank formed of uninsulated conductors which serve both as multiple conductors between the plurality of switching units and as wiper contacts for the wipers of the individual switching units, has been proposed in order to reduce the item of cost mentioned above. In switching apparatus of this type, the individual automatic switching units conventionally employed are of considerable size and complicated construction, and comprise a large number of elementary switches, thereby detracting from the inherent economy of the switching apparatus.

Accordingly, it is an obj ect of the present invention to provide an improved switching unit adapted to be used in conjunction with a bare wire bank contact and multiple eld, which comprises a minimum number of elementary switches of simple construction, which is positive in operation, and is compact and economical to manufacture.

Another object of the invention is to provide a switching unit having an improved reset mechanism for restoring the switching unit from an operated position to an idle position, which positively insures that the operated elements of the switching unit are returned to idle positions in a predetermined order.

A further object of the invention is to provide an automatic switching unit of this type which embodies an improved arrangement for indicating the idle or particular operated position of the switching unit.

A further object of the invention is to provide an improved elementary switch adapted to be incorporated in a switch unit of the form noted and comprising a minimum number of operating elements.

In general the objects as set forth above are attained, in accordance with the present invention, by providing a switching unit which comprises a plurality of elementary switches; each of Delaware 1938, Serial No. 214,722

the elementary switches including a carriage movable in a rst direction, an element carried by the carriage and movable in the second direction, and a contact controlling member carried by the element; means including a first operating member common to the elementary switches for selecting any one of the elementary switches to be operated; means including a second operating member common to the elementary switches for moving the carriage of a selected one of the elementary switches; and means including a third operating member common to the elementary switches for moving the element of the selected elementary switch. More specifically, each of the operating members is supported for longitudinal step-by-step movement. The step-by-step movement of the iirst operating member is effective to cause the carriages of the elementary switches to be locked in a predetermined order to the second operating member for longitudinal movement therewith, the step-by-step movement of the second operating member being effective to move the carriage of a selected one of the elementary switches step by step in the iirst-mentioned direction; while the step-by-step movement of the third operating member is eiective to move the element of the selected elementary switch step by step in the second-mentioned direction.

'In accordance with another feature of the invention, an improved arrangement is provided for operating and controlling the switching unit, which comprises an escapement mechanism adapted to control selectively and in a predetermined order the movements of the operating members. In accordance with a further feature of the invention, an improved reset mechanism is provided in each switching unit which insures that, in restoring the switching unit from an operated position to an idle position, the operating members are returned to idle positions in a predetermined order, thereby to prevent injury to the associated conductor bank. Provision is also made for indicating the idle or particular operated position of each switching unit. This is accomplished by providing each switching unit with an indicating mechanism comprising a plurality of movable members individually controlled by corresponding ones of the operating members.

The novel features believed to be characteristic of the invention are set forth with particularity in appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification taken in connection with the accompanylng drawings, in which Figure 1 is an end elevational view of the front and rear frames of a switching apparatus constructed and arranged in accordance with the present invention; Fig. 2 is a side elevational view of the front frame shown in Fig. 1; Fig. 3 is an enlarged side elevational view, partly in section, of a particular structural detail of the front frame, taken in the direction of the arrows 3 in Fig. 1; Fig. 4 is an enlarged sectional view of the particular structural detail of the front frame, taken along the line 4-4 in Fig. 2; Fig. 5 is an enlarged fragmentary end elevational view of the conductor bank and two of the switching units carried by the front and rear frames shown in Fig. l; Figs. 6, 7 and 8, taken together, are a fragmentary plan view of one of the automatic switching units of the switching apparatus; Fig. 9 is a plan view of one of the elementary switches embodied in the automatic switching unit illustrated, showing the elementary switch in an operated position; Fig. 10 is an end elevational view, partly in section, of the operated, elementary switch, taken along the line IU-IU in Fig. 9; Fig. 11 is a fragmentary side elevational view of a reset mechanism embodied in the switching unit illustrated, taken in the direction of the arrows l I-l I in Fig. 6; Fig. 12 is a sectional view of an element of the operating mechanism embodied in the switching unit illustrated, taken along the line l2-I2 in Fig. 6; Fig. 13 is an enlarged fragmentary end elevational view of an escapement mechanism embodied in the switching unit illustrated, taken in the direction of the arrows I3-l3 in Fig. 7; Fig. 14 is an end elevational view of an escapement control mechanism embodied in the switching unit illustrated, taken in the direction of the arrows lil- I4 in Fig. 7; Fig. 15 is a sectional view of the escapement control mechanism, taken along the line l5-l5 in Fig. 14; and Fig. 16 is a sectional view of an indicator embodied in the switching unit illustrated, taken along the line lB-IB in Fig. 6.

Referring more particularly to Figs. 1 and 2 of the drawings, there is illustrated a switching apparatus including front and rear frames 2D and 2l, respectively, the frames being of similar construction and each comprising a plurality of vertical and horizontal members 22 and 23, respectively, secured together in any suitable manner. The frames 20 and 2l are arranged back to back and secured together in spaced relation, a conductor bank 24 being arranged to occupy the space between the backs of the frames. The conductor bank 24 comprises a plurality of vertically disposed conductors arranged in five divisions; each division comprising two groups; each group comprising ten levels or subgroups; each subgroup comprising ten lines; and each line comprising a positive, a negative and a control conductor. Each conductor in each division in the conductor bank 24 is uninsulated and serves both as a multiple conductor between the automatic switching units and as a fixed wiper contact for the movable wipers of the individual switching units. Also, each conductor is retained in position in its division by a plurality of spaced-apart insulating members 25. The positive, negative, and control conductors in each division are segregated into three subdivisions which are arranged in the same manner. The line conductors in each subgroup in each subdivision are arranged in substantially the same vertical plane, each line conductor being spaced from the adjacent line conductor by a xed distance; and the levels or subgroups in each subdivision are arranged in substantially parallel vertical planes, each subgroup being spaced from the adjacent subgroup by a xed distance. The two groups in each division are so arranged that corresponding lines in each group are engaged simultaneously by two sets of wipers carried by the elementary switch associated with the division and included in the switching unit, as is more fully explained subsequently.

Each of the frames 20 and 2l ls adapted to support a group or' identical automatic switching units in vertical alignment and in such a manner that each switching unit has access to each line in the conductor bank 24. This is accomplished by providing a front frame 20 with a plurality of sets of supporting elements 26 and the rear frame 2| with a plurality of sets of supporting elements 2l. In each frame, each set of supporting elements is spaced in a vertical direction a xed distance from the adjacent set of supporting elements and comprises two horizontally aligned supporting elements respectively secured to the vertical members 22 disposed at the right-hand and left-hand ends of the frame. In order to prevent the switching units supported by the rear frame 2| from interfering with the switching units supported by the front frame 20, the sets of supporting elements 2l carried by the rear frame 2l are staggered in a vertical direction with respect to the sets of supporting elements 26 carried by the front frame 20. Thus, the switching units in one of the groups have access to sections of the conductor bank 24 disposed between the switching units of the other group, as illustrated in Fig. 5.

Each switching unit is provided with a base plate 28 which constitutes a shelf adapted to be supported upon one of the sets of supporting elements carried by one of the frames. As best shown in Figs. 3 and 4, the opposite ends of the base plate 28 of one of the switching units supported inthe front frame 20 rest upon the upper surfaces of the supporting elements of one of the sets of supporting elements 26. The base plate 28 is provided with an upstanding flange 29 extending along the front edge thereof which projects over the vertical members 22 disposed at the opposite ends of the front frame 20. The base plate 28 is secured in place at each end thereof by an arrangement including a screw 30 extending through an elongated opening 3l formed in the flange 29 and threaded into an opening in the vertical member 22. Also, an arrangement is provided for locking each end of the base plate 28 securely in place, which comprises a pair of screws 32 threaded in openings formed in the ange 29 and engaging the vertical member 22. The elongated openings 3l formed in the opposite ends of the ange 29 accommodate adjustment of the switching unit in a longitudinal direction with respect to the ends of the front frame 20, and the screws 30 and 32 accommodate adjustment of the switching unit in a lateral direction with respect to the front and back of the front frame 2|).

In placing a switching unit ln the front frame 20, the base plate 28 of the switching unit is first positioned upon the set of supporting elements 26 disposed at the desired level. The switching unit is then slid laterally into place and adjusted so that the same is in proper alignment with respect to the conductor bank 24. The screws 30 are then inserted through the elongated openings 3| formed in the opposite ends of the flange 29 and tightened into snug engagement with the flange 29. 'I'he screws 32 are then tightened into snug engagement with the vertical members 22 disposed at the opposite ends of the front frame 26, thereby securely retaining the switch unit in its adjusted position. The switching unit may be removed from the front frame 28 by withdrawing the base plate 28 after the screws 38 have been untlghtened and removed. I

Each automatic switching unit is provided with an arrangement, more fully described subsequently, for indicating the idle or particular operated position thereof, which includes a signal visible through an aperture 33 provided in an escutcheon plate 34 secured to the flange 29. Also, an opening 35 is formed in the flange 29 which is adapted to receive a plug in order to facilitate testing of the automatic switching unit.

Referring now to Figs. 6, 7 and 8, there is shown a fragmentary portion of one of the automatic switching units of the switching apparatus, which comprises five elementary switches of identical construction and respectively associated with the iive divisions of lines in the conductor bank 24. The illustrated elementary switches 49 and 4I, respectively, are associated with the nrst and fifth divisions of lines in the conductor bank 24, the rst division comprising the lilrst and second groups of ten levels or subgroups of lines each, and the fth division comprising the ninth and tenth groups of ten levels or subgroups of lines each. Each of the elementary switches comprises a carriage 42 individually provided with an element or slide 43 mounted thereon, a contact controlling member 44 being mounted upon the slide 43. The contact controlling member 44 carries two line selecting devices in the form of two sets of wipers, the first set of wipers being individual to the odd group in the associated division of lines, and the second set of wipers being individual to the even group in the associated division of lines. More particularly, the first set of wipers comprises the wipers 45, 46 and 41, which are adapted to engage the positive, negative and control conductors, respectively, of the lines in the odd group; while the second set of wipers comprises the wipers 48, 49 and 50, which are adapted to engage the positive, negative and control conductors, respectively, of the lines in the even group. Also, a terminal block is mounted on the slide 43 in order to extend electrical connections to the two sets of wipers.

The carriage 42 of each elementary switch is mounted on a longitudinal guide bar 52 carried by the base plate 28, as best shown in Figs. 9 and lO. The rear edge of the carriage 42 is provided with a downwardly extending ange 53 which slidably engages a cooperating guide plate 54 individual thereto. The guide plate 54 is secured to an upstanding flange 55 provided on the rear edge of the base plate 28. Each of the carriages 42 has a normal position and is movable along a longitudinal path into ten off-normal positions respectively corresponding to the ten levels or subgroups in the odd and even groups in the associated division of lines in the conductor bank 24. The movement of the slide 43 on the carriege 42 is guided at the front edge of the slide by a screw 56 which rides in a slot, not shown, provided in the carriage 42, and at the rear edge of the slide by two downwardly extending lugs 51 formed thereon which cooperate with two guide arms 58 provided on the carriage 42. Each of the slides 43 has a normal position and is movable along a lateral path into ten off-normal positions respectively corresponding to the ten lines in each level or subgroup in the odd and even groups in the associated division.

An arrangement including a hundred bar 59, a ten bar 60 and a unit bar 6I is provided for operating the elementary switches of the switching unit. These operating bars are common to the elementary switches and disposed in superimposed relation, the hundred bar 59 being the top bar and the unit bar 6I being the bottom bar in the arrangement. These operating bars are mounted for movement in a longitudinal direction by an arrangement including a plurality of spaced-apart brackets 62 secured by screws 63 to the base plate 28, each operating bar being independently movable. Each of the operating bars has a normal position and is movable toward the left into ten off-normal positions. The

movements of the bars toward the left when they reach their tenth off-normal positions are arrested by a stop 62 secured to the base plate 28 by screws 62h.

The hundred bar 59 carries iive lugs thereon respectively associated with the iive elementary switches, the illustrated lugs 64 and 65 being respectively associated with the elementary switches 49 and 4|. Each of the lugs is provided with an off-set ringer which is adapted to engage a latch mounted on the carriage of the associated elementary switch. 'I'he lugs 64 and 65 are provided with oi-set ngers 64a and 65", respectively, which are adapted respectively to engage latches 66 and 61 pivotally mounted on the carriages 42 of the elementary switches 40 and 4I, respectively. The latch 66 is pivotally mounted at 68 upon the carriage 42 of the elementary switch 40 and is biased by a spring, not shown, away from an associated slot 69 formed in a bar 10 rigidly secured by a strap 1| to the ten bar 60. When the finger 64a on the lug 64 engages the latch 66', the latter is moved into the associated slot 69 in order to lock the carriage 42 of the elementary switch 40 to the bar 16 for movement in a longitudinal direction with the ten bar 60, thereby selecting the elementary switch 40 to be operated or rendering the elementary switch 40 operable to select a line from the first and second groups in the first division of lines in the conductor bank 24. The latch 61 is constructed in a similar manner, being adapted to be moved into an associated slot 12 formed in the bar 1D, when the latch 61 is engaged by the nger 65a on lug 65. The lugs 64, etc., are successively spaced along the hundred bar 59 and arranged in such a manner that the fingers on the lugs successively engage the latches mounted on the carriages of the elementary switches as the hundred bar 59 is moved from its normal position, each finger being arranged to engage the latch associated therewith when the hundred bar 59 occupies two adjacent off-normal positions. Thus, the finger 64l engages the latch 66 when the hundred bar 59 is moved from its normal position into its first oil-normal position, thereby locking the carriage 42 of the elementary switch 40 to the bar 10; and the ringer 64a remains in engagement with the latch 66 when the hundred bar 59 is moved into its second off-normal position. The latch 66 rides oil of the end of the nger 64e on the lug 64 carried by the hundred bar 59 when the hundred bar 59 is moved into its third off-normal position, thereby unlocking the carriage 42 of the elementary switch 40 from the bar 10. Thus,

the carriage of the rst elementary switch 40 is locked to the bar 10 when the hundred bar occupies its first and second off-normal position; the carriage of the second elementary switch is locked to the bar 10 when the hundred bar 59 occuplies its third and fourth off-normal position; etc. The arrangement of the lugs 64, etc., on the hundred bar 59 allows only one of the elementary switches to be rendered operable or to be selectedv for operation at any time; and any one of the elementary switches may be selected to be operated by moving the hundred bar to a corresponding off-normal position.

After the hundred bar 59 has been moved from its normal position into a predetermined .offnormal position to cause a corresponding elementary switch to be selected and the carriage thereof to be locked to the bar 10, the ten bar 60 is moved from its normal position into a predetermined off-normal position, causing the carriage 42 of the selected elementary switch to be moved longitudinally toward the left from its normal position into a corresponding off-normal position, thereby to select corresponding levels or subgroups from the odd and even groups in the associated division of lines in the conductor bank 24. The carriage 42 of the selected elementary switch is moved with the ten bar 60 due to the engagement between the latch mounted on the carriage 42 of the selected elementary switch and the associated slot formed in the bar 10 rigidly secured to the ten bar 60. The latch is retained in position in the associated slot during the movement of the ten bar 60 by a member individual to the selected elementary switch and having a guide edge associated with the latch. The illustrated members 12 and 13 are individual to the elementary switches 40 and 4|, respectively, and have the guide edges 14 and 15 respectively associated with the latches 66 and 61, respectively. The members 12 and 13 are secured to a bar 'I6 by two sets of screws 11 and 18, respectively, the bar 16 being secured to the brackets 62. This arrangement positively insures that the carriage 42 of the selected elementary switch is locked to the bar 10 during the entire longitudinal movement of the bar 10 with the ten bar 60.

After the ten bar 60 has been moved from its normal position into a predetermined offnormal position, causing the carriage 42 of the selected elementary switch to be moved from its position into a corresponding OIT-normal position, thereby to select corresponding levels or subgroups from the odd and even groups in the associated division of lines, the unit bar 6| is moved from its normal position into a predetermined oil-normal position. This movement of the unit bar 6| causes the slide 43 mounted on the carriage 42 of the selected elementary switch to be moved laterally from its normal position into a corresponding ofi-normal position, thereby to select corresponding lines from the previously selected levels or subgroups of lines. This movement of the slide 43 in response to the movement of the unit bar 6| is effected by an arrangement including an under-slide 19 and a bell crank individual to the selected elementary switch, as is best shown in the operated elementary switch in Figs. 9 and 10. The underslide 19 is mounted for movement in a lateral direction upon two substantially parallel lat- .erally extending guide members secured to the base plate 28. One of these guide members comprises two aligned rods 8|- and 8|, while the other guide member comprises an angle bar 82. The under-slide 19 is provided with two outwardly extending arms 83 and 84 embracing the guide rods 8|b and 8| and an outwardly extending arm 85 engaging the guide bar 82 in order to guide the lateral movement of the under-slide 19. Also, an upstanding ange 86 is provided on the rear edge of the under-slide 19 which slidably engages a downwardly projecting button 81 carried by the slide 43 of the selected elementary switch, the button 81 having a slot therein which straddles the upper edge of the flange 86. This arrangement allows the carriage 42 and the slide 43 of the selected elementary switch to be moved longitudinally with respect to the under-slide 19 without any interference therewith.

The bell crank 80 is pivotally mounted at 88 upon a bracket 89 secured by screws 90 to the base plate 28. The bell crank 80 is provided with three outwardly extending arms 9|, 92 and 93 and is biased in a clockwise direction by coil spring 94'extending between the outer end of the arm 9| and a fixture 95 carried by the base plate 28. The outer end of the arm 93 carries a roller 96 which engages an elongated slot 91 provided in the under-slide 19, the engagement between the roller 96 and the slot 91 constituting a driving engagement between the bell crank 80 and the under-slide 19. 'The outer end of the arm 92 engages an upstanding ange 98 provided on a fixture 99 secured to the unit bar 6| by a screw |00.

A locking arrangement is provided in each elementary switch in order to control the movement of the slide 43 thereof. The locking arrangement individual to the elementary switch 4| comprises a. locking plate |0| secured t0 a bar |02 by screws |03, the bar |02 being secured to the brackets 62. The locking plate |0| is provided with a downwardly extending ange |04 having ten notches |05 therein which correspond to the ten olf-normal positions of the carriage 42 and cooperate with an upstanding ange |06 provided on one side of the slide 43 adjacent the rear end thereof. More specifically, the rear end of the flange |06 engages the flange |04, when the carriage 42 of the elementary switch 4| occupies its normal position, thereby to lock the slide 43 of the elementary switch 4| in its normal position against movement in a lateral direction. When the elementary switch 4| is selected to be operated and the carriage 42 thereof is moved longitudinally from its normal position into a predetermined oi-normal position, the rear end of the flange |06 is moved into alignment with a corresponding notch |05 in the flange |04, thereby to unlock the slide 43 for movement in a lateral direction, the slide 43 being restrained against movement in a lateral direction by the engagement between the flange 98 on the xture 99 secured to the unit bar 6| and the outer end of the arm 92 on the bell crank 80, at this time.

After the carriage 42 of the selected elementary switch 4| has been moved longitudinally into a predetermined off-normal position by the ten bar 60, the unit bar 6| is moved longitudinally toward the left into a predetermined off-normal position. As the unit bar 6| is moved longitudinally, the flange 98 on the fixture 99 is moved away from the outer end of the arm 92 on the bell crank 80, causing the spring 94 to rotate the bell crank 80 in a clockwise direction about the pivot 88. It is noted that the flange 98 on the fixture is sufficiently wide to prevent the outer end of the arm 92 on the bell crank 00 from disengaging the flange 98 as the bell crank 80 is rotated in a clockwise direction about the pivot 88. Rotation of bell crank in a clockwise direction causes the under-slide 19 to be moved laterally toward the rear of the switching unit through the driving engagement between the roller 96 carried by the arm 93 on the bell crank 80 and the slot 91 in the under-slide 19. This movement of the under-slide 19 is transmitted to the slide 43 through the driving engagement between the flange 86 on the under-slide 19 and the button 81 carried by the slide 43. The lateral movement of the slide 43 is the same as that of the under-slide 19, which latter movement is proportional to the rotational movement of the bell crank 80, while the rotational movement of the bell crank 80 is proportional to the longitudinal movement of the unit bar 6|. Thus, the movement of the slide 43 is proportional to the movement of the unit bar 6|, and when the unit bar 6| is moved from its normal position into a predetermined off-normal position, the slide 43 is moved from its normal position into a corresponding off-normal position.

From the above it will be understood that the slide 43 of only the selected elementary switch 4| will be moved laterally when the unit bar 6| is moved longitudinally, due to the fact that the rear or right-hand end of the flange |06 on the slide 43 of only the selected elementary switch 4| will be aligned with a notch |05 in the flange |04 on the locking plate |0|, as shown in Fig. 10. The rear ends of the flanges |06 on the slides 43 of the remainder of the elementary switches engage the flanges |04 on the locking plates |0| associated therewith, thereby locking the slides 43 of the remainder of the elementary switches against lateral movement. When the slide 43 of the selected elementary switch 4| is moved into its first off-normal position the flange |06 thereon enters the notch |05 in the flange |04 on the locking plate |0|. This engagement between the flange |06 and the notch |05 in the flange |04 locks the carriage 42 of the selected elementary switch 4| against further movement in a longitudinal direction.

The rear edge of the carriage 42 of each elementary switch carries three insulating buttons |01, |08 and |09, respectively, arranged between the positive wipers 45 and 48, the negative wipers 46 and 49, and the control wipers 41 and 50, carried by the contact controlling member 44 mounted on the slide 43 thereof. These buttons cooperate with inwardly bent portions of the associated wipers in order to prevent vibration of and engagement between the respective positive, negative and control wipers of the first and second contact sets, when the slide 43 of the elementary switch occupies its normal position. When the slide 43 of the selected elementary switch is moved from its normal position into its first off-normal position, the wipers of the first and second contact sets are moved respectively into engagement with the first lines of the adjacent levels or subgroups in the odd and even groups in the associated division of lines, and the inwardly bent portions of the wipers are moved out of engagement with the associated insulating buttons |01, |08 and |09. Also, each of the guide rods 8|a is provided with a stop ||0 in order to arrest the movement of the under-slide 19, when the unit bar 6| is restored to its normal position. This stop ||0 limits the lateral movement of the slide 43 of the elementary switch by engaging the arm 84 on the under-slide 19, and insures that the slide 43 will be arrested in its normal position.

In order to restore the operated elementary switch 4| to its idle position, the unit bar 6| is first moved toward the right back into its normal position. This movement of the unit bar 6| causes the bell crank 80 to be rotated in a counterclockwise direction about the pivot 88 against the bias of the spring 94, due to the driving engagement between the flange 98 on the fixture 99 secured to the unit bar 6| and the outer end of the arm 92 on the bell crank 80. This counterclockwise rotation of the bell crank 80 moves the under-slide 19 laterally toward the front of the switching unit through the driving engagement between the roller 96 carried by the outer end of the arm 93 on the bell crank 80 and the slot 91 in the under-slide 19. 'Ihis movement of the under-slide 19 is transmitted to the slide 43 through the driving engagement between the flange 86 on the under-slide 19 and the button 81 carried by the slide 43, causing the slide 43 to be moved laterally toward the front or lefthand end of the switching unit, as shown in Fig. 10, back into its normal position. When the slide 43 is moved back into its normal position, the flange |06 thereon disengages the notch |05 in the flange |04 on the locking plate |0 thereby to unlock the carriage 42 of the elementary switch 4| for movement in a longitudinal direction back into its normal position. The ten bar 60 is then moved toward the right back into its normal position, causing the carriage 42 to be moved toward the right back into its normal position through the driving engagement between the latch mounted on the carriage 42 and the associated slot in the bar 10 rigidly secured to the ten bar 60. When the carriage 42 is moved back into its normal position, the rear end of the flange |06 on the slide 43 reengages the flange |04 on the locking plate |0|, thereby to lock the slide 43 of the elementary switch against movement toward the rear of the switching unit. Finally, the hundred bar 59 is moved toward the right back into its normal position, causing the finger 65 on the lug 65 carried by the hundred bar 59 and associated with the latch 61 mounted on the carriage 42 of the selected elementary switch 4| to disengage the latch, thereby allowing the spring biased latch to move out of the associated slot 12 in the bar 10, in order to unlock the selected elementary switch from the bar 10 and to restore the same to its idle position. Thus, the switching unit is completely restored to its idle position at this time and may be reoperated as described above in order to select corresponding lines from sub-groups in the odd and even groups in any division of lines in the conductor bank 24.

In order to control the operating bars 59, 60 and 6| in the switching unit in the manner de scribed above, an operating mechanism is provided which includes an escapement mechanism and a reset mechanism H2, shown in Figs. 6, "I, and 11 to 16, inclusive. The escapement mechanism includes three identical gears ||3, ||4 and ||5 rotatably mounted on a fixed shaft ||6, one end of the shaft ||6 being fixed to the base plate 28, and the other end thereof being fixed to a bracket ||1 secured by screws 8 to the base plate 28. The gears ||3, ||4 and ||5 are associated, respectively, in driving engagement with three racks H9, |20 and |2|, which are respectively secured to the operating bars 59,

60 and 6 the rack |9 being secured to the hundred bar 59 by a rivet illustrated at |22. The racks ||9, |20 and |2| are biased toward the left by three operating levers |23, |24 and |25 respectively secured thereto by pin and slot connections |26, |21 and |28, respectively. The levers |23, |24 and |25 are of identical construction, each being pivoted at one end to a pin |29 secured to the base plate 28 and being biased by a spring |30 individual thereto in a clockwise direction about the pivot pin |29. One end of each of the springs |30 is iixed to a pin I3| secured to the base plate 28 and the other end thereof is fixed to a corresponding one of the levers |23, |24 and |25. The gears ||3, ||4 and ||5 are restrained against movement in a counterclockwise direction by the associated driving racks H9, |20 and |2|, respectively, by toothed escapement wheels |32, |33 and |34 respectively secured thereto. The escapement wheels |32, |33 and |34 are provided with escapement members |35, |36 and |31, respectively, pivotally mounted on a pin |38 secured between the bracket I I1 and the base plate 28. The escapement members |35, |36 and |31 are of identical construction, and each comprises an escapement pawl and an outwardly extending operating arm. Each of the escapement members is biased in a clockwise direction about the pivot pin |38 by a spring individual thereto, in order to bring the escapement pawl thereon into engagement with the associated escapement wheel. More specifically, the escapement member comprises an escapement pawl |39 and an outwardly extending operating arm |40 and is biased by a spring 4| in a clockwise direction about the pivot pin |38, in order to bring the escapement pawl |39 into engagement with the associated escapement wheel |32. One end of each of the springs individual to the escapement members |35, |36 and |31 is fixed to a pin |42 secured to the base plate 28, and the other end thereof is fixed to a corresponding one of the escapement members.

The escapement mechanism also includes an operating motor MI of the electromagnetic type, comprising a winding |43 and a magnetic structure including a core |44, a frame |45 and an armature |46. The armature |46 is pivotally mounted to the frame |45 by a pin |41 and is biased in a clockwise direction about the pivot pin |41 away from the core |44 into engagement with a stop |48 by a coil spring |49, one end of the spring |49 being xed to the armature |46 and the other end thereof being fixed to a pin |50 secured to the base plate 28. An arrangement including a plate |5| secured to the armature |46 by a screw |52 and provided with a striking flange |53 extending toward the operating arms of the escapement members |35, |36 and |31 is provided for operating the escapement members, thereby to rotate the escapement members in a counterclockwise direction about the pivot pin |38 in order to move the escapement pawl thereon out of engagement with the associated escapement wheels |32, |33 and |34.. When one of the escapement members is thus rotated to move the escapement pawl thereon out of engagement with the associated escapement wheel, the associated escapement wheel allows the gear secured thereto to-be driven in a counterclockwise direction by the associated rack in driving engagement therewith, thereby to move the associated operating bar longitudinally toward the left.

An arrangement including a mechanism |54 is provided in order to control the escapement mechanism I. This escapement control mechanism |54 comprises a ratchet wheel |65 rotatively mounted upon a fixed pin |56 secured to the base plate 28, and three substantially disc-shaped cam members |51, |58 and |59 rigidly secured to the ratchet wheel |55, as best shown in Figs. '1, 14 and 15. The periphery of each of the cam members is provided with a plurality of projections which are spaced apart by intervening depressions. More specicially, the cam member |51 is provided with four projections |51 which are spaced apart by intervening depressions |511. In a similar manner, the cam members |58 and |59, respectively, are provided with four projections |58 and |59, which are respectively spaced apart by intervening depressions |58 and |591. Three bell cranks |60, |6| and |62 are respectively associated with the cam members |51, |58 and |59, these bell cranks being pivotally mounted on a pin |63 extending between the bracket ||1 and the base plate 28. Each of the bell cranks is provided with two outwardly extending arms, the extreme outer end of one of the arms having a. finger adapted to ride upon the periphery of the associated cam member. More specifically, the bell crank |60 is provided with two outwardly extending arms |60 and |60b, the extreme outer end of the arm |60a having a finger |60c adapted to ride upon the periphery of the associated cam member |51. In a similar manner, the bell cranks |6| and 62 are respectively provided with two outwardly extending arms |6|a, |6|b and |62, |62b, the extreme outer ends of the arms |6| and |623 being respectively provided with iingers |||c and |62c adapted respectively to ride upon the peripheries of the cam members |58 and |59. Three tappets |64, |65 and |66 are respectively pivotally secured by rivets |61, |68 and |69, respectively, to the arms |6011, |6|b and |62", respectively, of the bell cranks |60, |6| and |62, respectively. Each of the tappets is provided with a head to which one end of a coil spring individual thereto is fixed, the other end of the spring being xed to a pin |10 secured to the base plate 28. More specifically, the tappet |64 is provided with a head |64a to which one end of the coll spring |1| individual thereto is fixed, the other end of the spring |1| being fixed to the pin |10. In a similar manner, the tappets 65 and 66 are provided, respectively, with heads |65a and |66a to which the coil springs |12 and |13 individual to the tappets |65 and |66, respectively, are secured, the other ends of the springs |12 and |13 being secured to the pin |10. The tappets |64, |65 and |66 are arranged between the operating arms of the escapement members |35, |36 and |31 and the striking flange |53 provided on the plate |5| secured to the armature |46. Normally, the springs |1|, |12 and |13 bias the heads |649, |65E and |663, respectively of the tappets |64, |65 and |66, respectively, toward the front of the switching unit out of positions of engagement with the striking iiange |53. The biases of the springs 1|, |12 and |13 cause the bell cranks |60, |6| and |62, respectively, to be rotated in a clockwise direction about the pivot pin |63, thereby bringing the fingers |609, |6|c and |629, respectively, into engagement with the peripheries of the cam members |51, |58 and |59, respectively.

The escapement control mechanism |54 is so constructed and arranged that when the finger on the extreme outer end of one of the arms of the bell crank engages one of the depressions in the periphery of the assiciated cam member, the bell crank is rotated in a clockwise direction about the pivot pin |63 by the coil spring extending between the pin |10 and the head of the tappet pivotally mounted on the other arm of the bell crank, thereby causing the head of the tappet to be moved out of striking position with respect to the striking flange |53 on the plate |5| carried by the armature |46. On the other hand, when the finger on the extreme outer end of one of the arms of a bell crank engages one of the projections on the periphery of the associated cam member, the bell crank is rotated in a counterclockwise direction about the pivot pin |63 against the bias of the coil spring extending between the pin |10 and the head of the tappet pivotally mounted on the other arm of the bell crank, thereby causing the head of the tappet to be moved into striking position with respect to the striking flange |53 on the plate |5| secured to the armature |46. The movements of the tappets into their striking positions are limited by a stop |10 carried by the base plate 28.

More specifically, when the finger |60c on the extreme outer end of the arm |60a of the bell crank |60 engages one of the depressions |51b in the periphery of the associated cam member |51, the bell crank |60 is rotated in a clockwise direction about the pivot pin |63 by the coil spring |1| extending between the pin |10 and the head |64 of the tappet |64 pivotally mounted by the rivet |61 on the arm |60b of the bell crank |60, thereby causing the head |64a of the tappet |64 to be moved out of striking position with respect to the striking flange |53 on the plate |5| carried by the armature |46. On the other hand, when the finger |60c on the extreme outer end of the arm ll)a of the bell crank l 60 engages one of the projections |51El on the periphery of the associated cam member |61, the bell crank |60 is rotated in a counter-clockwise direction about the pivot pin |63 against the bias of the coil spring |1| extending between the pin |10 and the head |64f of the tappet |64 pivotally mounted by the rivet |61 on the arm |60b of the bell crank |60, thereby causing the head |64SL of the tappet |64 to be moved into striking position with respect to the striking flange |53 on the plate |5| carried by the armature |46. The construction and arrangement of each of the bell cranks |6| and |62 associated with the cam members |58 and |59, respectively, is the same as that of the bell crank |60 described above.

When the head of any one of the tappets is moved into striking position with respect to the striking flange |53 on the plate 5| carried by the armature |46, the associated escapement member pivotally mounted on the pin |38 is conditioned to be operated to allow the associated escapement wheel to be rotated in a counterclockwise direction by the associated rack in driving relation with the gear secured thereto. More specifically, when the head |643 of the tappet |64 is moved into striking position with respect to the striking flange |53, the associated escapement member |35 pivotally mounted on the pin |38 is conditioned to be operated to allow the associated escapement wheel |32 to be r0- tated in a counterclockwise direction by the associated rack ||9 in driving relation With the gear ||3 secured thereto.

At this time, when the operation motor Mi is energized, the armature |46 thereof is moved in a counterclockwise direction about the pivot pin |41 against the bias of the coil spring |49, causing the striking flange |53 on the plate |5| carried by the armature |46 to engage the head |64 of the tappet |34. The head |64 of the tappet |64 is then moved into engagement with the arm |40 on the escapement member |36, thereby to cause the escapement member |36 to be rotated in a counterclockwise direction about the pivot pin |38 against the bias of the coil spring |4|. When the escapement member |35 is rotated in a counterclockwise direction, the escapement pawl 39 is moved out of engagement with the escapement wheel |32, thereby allowing the rack ||9 in driving engagement with the gear ||3 secured to the escapement wheel |32 to move the escapement wheel |32 one step ln a counterclockwise direction, further movement of the escapement wheel in a counterclockwise direction being arrested by the inwardly curved finger |40'L provided on the operating arm |40. The finger |40ai on the operating arm |40 serves as a detent to prevent further counterclockwise rotation of the escapement wheel |32. The rotation of the escapement wheel |32 one step in a counterclock- Wise direction allows the rack ||9 to be moved longitudinally one step toward the left by the lever |23 mounted on the pivot pin |29 and pivotally secured by the pin and slot connection |26 to the rack ||9, this movement of the rack I9 being produced by rotation of the lever |23 in a clockwise direction about the pivot pin |29 under the influence of the coil spring |30. This movement of the rack I9 is transmitted to the hundred bar 59 connected to the rack I| 9, causing the hundred bar to be moved longitudinally one step from its normal position into its first oli-normal position, thereby to cause the first elementary switch 40 to be selected to be operated as previously explained. When the operating motor M| is deenergized, the armature |46 thereof is rotated in a clockwise direction about the pivot pin |41 by the coil spring |49, causing the head |64 of the tappet |64 to disengage the operating arm |40 of the escapement member |35, thereby allowing the escapement member |35 to be rotated in a clockwise direction about the pivot pin |38 by the coil spring |4 When the escapement member |35 is rotated in a clockwise direction, the detent |40 disengages the escapement wheel |32 shortly before the escapement pawl |39 on the escapement member |35 engages the escapement wheel |32, the escapement pawl 39 retaining the escapement wheel against further counterclockwise movement, at this time. Upon each subsequent energization of the operating motor MI, the escapement wheel |32 is rotated a corresponding step in a counterclockwise direction as described above. Thus, the hundred bar 59 is moved longitudinally toward the left step by step a predetermined number of steps corresponding to the number of times the operating motor M1 is repeatedly energized, thereby causing a corresponding one of the elementary switches to be selected to be operated, as previously explained.

The striking flange |53 on the plate |5| carried by the armature |46 is sufficiently long to engage the head of any one of the tappets |64, |65 and |66, which occupies a striking position. Thus, it will be apparent that the hundred bar 59, the ten bar 60 and the unit bar 6| may be selectively operated by selectively moving the heads of the tappets |64, |65 and |66 into striking positions, the number of steps which any one of the operating bars is moved longitudinally toward the left being dependent upon the number of times the operating motor Ml is repeatedly energized while the head of the corresponding tappet occupies a striking position. From the foregoing it is apparent that the operating bars 59, 60 and 6| may be selectively moved from their normal positions into any one of their oit-normal positions by selectively controlling the movements of the tappets |64, |65 and |66, and by selectively controlling the number of times the operating motor MI is repeatedly energized when the tappets occupy striking positions.

The escapement control mechanism |54 also includes an operating motor M2 of the electromagnetic type, comprising a winding |14 and a magnetic structure including a core |15, a frame |16 and an armature |11. The armature |11 is pivotally mounted to the frame |16 by a pin |18 and is provided with an outwardly extending arm |19 which is biased by a coil spring |80 into engagement with a stop |8|. One end of the coil spring is fixed to the arm |19 and the other end thereof is fixed to a pin |82 secured to the base plate 28, while the stop |8| is carried by a bracket |83 secured by screws |84 to the base plate 28. A pawl |85 is pivotally mounted by a pin |86 to the extreme outer end of the arm |19 and is biased in a clockwise direction about the pivot pin |86 by a coil spring |81 extending between the pawl |85 and the arm |19. The pawl |85 is biased by the spring |81 into engagement with the associated ratchet wheel |55 and the movement thereof is guided by a guide bracket |88 secured by a. screw |89 to the base plate 28. Also, a detent |90 pivotally mounted on a pin |9| secured to the base plate 28 is provided in order to retain the ratchet wheel |55 in any one of its operated positions, the detent |90 being biased by a spring |9| into engagement with a stop |92 secured to the base plate 28. When the winding |14 of the operating motor M2 is energized the armature |11 is moved in a counterclockwise direction about the pivot pin |18, causing the pawl |85 carried by the arm |19 to be moved away from the associated ratchet wheel |55 against the bias of the spring |80. When the Winding |14 of the operating motor M2 is then deenergized, the armature |11 is rotated in a clockwise direction about the pivot pin |18 by the spring |80, causing the arm |19 to be moved into engagement with the stop |8I, thereby to cause the pawl |85 to engage the ratchet wheel |55. The engagement of the pawl |85 and the associated ratchet wheel |55 causes the ratchet wheel |55 to be rotated one step in a clockwise direction, the ratchet wheel being retained in this operating position by the detent |90. Each time the winding |14 of the operating motor M2 is energized and then deenergized, the ratchet wheel |55 is rotated one step in a clockwise direction as explained above.

The four projections on each of the cam members |51, |58 and |59 are equally spaced apart a distance equal to ve steps of the ratchet wheel |55 to which each of the cam members is secured, and the cam members are so arranged with respect to each other that the projections on the peripheries thereof are disposed in staggered relation in a manner more particularly described below. When the switching unit occupies an idle position, the ratchet wheel occupies a normal position wherein the ngers |60, |6|c and |62c engage depressions |51, |58b and |59b in the peripheries of the cam members |51, |58 and |59, respectively thereby causing the heads of the tappets |64, |65 and |66 to occupy their non-striking positions, as previously explained. When the switching unit is operated, the ratchet wheel |55 is rst rotated one step in a clockwise direction into a iirst off-normal position wherein the nger |60c engages a projection |51a on the periphery of the cam member |51 and the :fingers |6|c and |62 respectively engage depressions |58b and |59b formed in the peripheries of the cam members |58 and |59, respectively, thereby causing the head of the tappet |64 to be moved into its striking position and the heads of the tappets |65 and |66 to be retained in their non-striking positions. The ratchet wheel |55 is then rotated into a second off-normal position wherein the nger |6| engages a projection |58a on the periphery of the cam member |58 and the fingers |60'J and |62c respectively engage depressions |5111 and |59b formed in the peripheries of the cam members |51 and |59, respectively, thereby causing the head of the tappet |65 to be moved into its striking position and the heads of the tappets |64 and |66 to occupy their non-striking positions. The ratchet wheel |55 is then rotated into a third off-normal position wherein the finger |62c engages a projection |59a on the periphery of the cam member |59 and the lingers |60c and |6|c respectively engage depressions |51b and |58b formed in the peripheries of the cam members |51 and |58, respectively, thereby causing the head of the tappet |66 to be moved into its striking position and the heads of -the tappets |64 and |65 to occupy their non-striking positions. The ratchet Wheel |55 is then rotated into a fourth off-normal position wherein the fingers |600, |||c and |62c engage depressions |5111, |581 and |59b in the peripheries of the cam members |51, |58 and |59, respectively, thereby causing the heads of the tappets |64, |65, and |66 to occupy their non-striking positions. When th-e operated switching unit is restored to its idle position, the ratchet wheel |55 is rotated into a fth off-normal position wherein the fingers |60, |61c and |62c engage depressions |511), |58b and |59b in the peripheries of the cam members |51, |58 and 59, respectively, as explained in connection with the positions of the ngers when the ratchet wheel |55 occupies its normal position, the fth off-normal position of the ratchet wheel |55 constituting a normal position thereof for the next cycle of operation of the switching unit.

The reset mechanism ||2 comprises an operating motor M3 including a magnetic structure having two core legs |93 and |94 displaced substantially 90 with respect to each other and provided with energizing windings |95 and |96, respectively. The operating motor M3 also includes a frame |91 secured by a number of screws |98 to the base plate 28, and a bracket |99 secured by a number of screws 200 to the frame |91. A rotor 20| is disposed between the core legs |93 and |94 and is rotatably mounted between the frame |91 and the bracket |99. The rotor 20| includes two diametrically disposed pole pieces 202, each provided with an elongated leading pole tip 2028. A commutator arrangement is provided for the operating motor M3, which includes a substantially disc-shaped insulating cam 203 mounted on the rotor 20| and two contact sets 204 and 205, in order to control the energization of the windings |95 and |96. The contact set 204 includes two cooperating resilient contact springs 206 and 201 biased into engagement and movable into disengagement, and the contact set 205 includes two cooperating resilient contact springs 208 andA 209 biased into engagement and movable into disengagement. The contact springs 201 and 209 of the contact sets 204 and 205, respectively, are extended into engagement with the periphery of the insulating cam 203, these contact springs being adapted to ride upon the periphery of the insulating cam. The periphery of the cam 203 is provided with two diametrically disposed projections 203EL having gradually inclined surfaces therebetween, the arrangement being such that the contact springs of the Contact sets 204 and 205 are alternately engaged. The windings |95 and |96 are energized in parallel circuit relation from a suitable source of direct current supply. The contact set 204 is included in series circuit relation with the winding |96, and the contact set 205 is included in series circuit relation with the winding |95.

This commutator arrangement causes the contact springs of the contact set 204 to be disengaged and the contact springs of the contact set 205 to be engaged, when the leading edge o1' the pole tip 202a on one of the pole pieces 202 occupies a position adjacent the leading tip of the core leg |93, thereby to cause the winding |95 to be energized and the winding |96 to be deenergized. Also, this commutator arrangement causes the contact springs of the contact set 204 to be engaged and the contact springs of the contact set 205 to be disengaged, when the leading edge of the pole tip 202* on one o! the pole pieces 202 occupies a position adjacent the leading tip of the core leg |94, thereby to cause the winding |96 to be energized and the winding |95 to be deenergized. The alternate energization 0f the windings |95 and |96 causes the rotor 20| to be rotated in a clockwise direction in a well known manner.

The rotor 20| of the operating motor M3 is arranged in driving relation with a reset cam member 2 I 0 rigidly secured to a pin 2| rotatably supported by the base plate 29. The reset cam member 2|0 is driven by the rotor 20| through a gear train including a pinion 2|2 rigidly secured to the shaft of the rotor 20|. The pinion 2|2 is arranged in driving relation with a gear 2|3 rotatably supported on a pin 2|4 and secured to the base plate 28. The gear 2|3 is rigidly secured to a pinion 2|5 arranged in driving relation with a gear 2|6 rigidly secured to a pin 2|'| rotatably supported by the base plate 28, Also, a pinion 2|8 is rigidly secured to the pin 2| and arranged in driving engagement with a gear 2|9 rigidly secured to the pin 2||. The cam member 2| 0 carries a roller 220 and the gear 2|9 carries a roller 22|, the roller 220 being associated with two reset ngers |23a and |24"A provided on the operating levers |23 and |24, respectively, and the roller 22| being associated with a reset nger |25a provided on the operating lever |25. The roller 220 is adapted to engage the ends of the fingers |23 and |24 when the cam 2|| is rotated in a counterclockwise direction by the operating motor M3, in order to cause the levers |23 and |24 respectively to be rotated in a counterclockwise direction about the pivot pin |29, thereby to cause the hundred bar 59 and the ten bar 60 to be moved longitudinally toward the right from their predetermined onf-normal positions back into their normal positions. In a similar manner, the roller 22| is adapted to engage the end of the finger |25a when the gear 2|9 is rotated in a counterclockwise direction by the operating motor M3, in order to cause the lever |25 to be rotated in a counterclockwise direction about the pivot pin |29, thereby to cause the unit bar 6| to be moved longitudinally toward the right from its predetermined off-normal position back into its normal position. The rollers 220 and 22| are disposed angularly with respect to each other in such a manner that the roller 22| is brought into engagement with the finger |25 before the roller 220 is brought into engagement with the fingers |23 and |24", thereby causing the unit bar 6| to be moved back into its normal position prior to the movement of the ten bar S0 and the hundred bar 59 back into their normal positions.

From the above, it will be understood that the pin 2|| to which the cam member 2|0 and the gear 2|9 are secured must be rotated one revolution in a counterclockwise direction in order to release the switching unit and return the same to its idle position. In order to insure that the pin 2|| is rotated exactly one revolution when the operating motor M3 is energized, an arrangement is provided which includes a contact set 222 supported by the bracket |99. The contact set 222 includes a pair of cooperating flexible contact springs 223 and 224 normally biased into disengagement and adapted to be moved into engagement by the cam member 2|0, the contact spring 224 being provided with an extended portion adapted to ride upon the periphery of the cam member 2|0. The contact set 222 is included in a secondary energizing circuit for the operating motor M3. In releasing the switch unit, the operating motor M3 is first energized by way of a primary energizing circuit independent of the contact set 222, and after a predetermined rotation of the cam member 2 l0, the contact springs of the contact set 222 are engaged. Shortly thereafter, the primary energizing circuit of the operating motor M3 is interrupted, the operating motor being energized only by way of the secondary energizing circuit. After the cam member 2|0 has been rotated one revolution, the projecting end of the contact spring 224 rides into a depression 2|0a provided in the periphery of the cam member 2|0, causing the contact springs of the contact set 222 to be disengaged. thereby to interrupt the secondary energizing circuit of the operating motor M3 and to arrest operation thereof.

An arrangement is provided for indicating the idle or particular operated position of the switchu ing unit which comprises three levers 225, 226 s and 221 pivotally mounted intermediate their ends upon a pin 228 provided on a standard 229 secured by screws 230m to the base plate 28. One end of each of the levers carries a flag bearing indicia and the other end thereof is pivotally secured to a corresponding one of the racks ||9, |20 and |2|. More specifically, one end of the levers 225, 226 and 221 carries a flag 230, 23| and 232, respectively, and the other end thereof is secured to the racks H9, |20 and |2| by the pin and slot connections |26, '|21 and |28, respectively. Each of the flags is associated with the aperture 33 provided in the escutcheon plate 34 secured to the flange 29 extending along the front edge of the switching unit. The indicia provided on each flag comprises one letter and ten numerals arranged in spaced relation thereon, which are adapted to be moved individually into alignment with the aperture 33 in the escutcheon plate 34, and which correspond to the normal and the ten oil-normal positions of the associated operating bar. When the switching unit occupies an idle position, the operating bars 59, and 6| occupy their normal positions and the letter N" is visible through the aperture 33 ln the escutcheon plate 34 on each of the ags 230, 23| and 232. On the other hand, when the switching unit is operated to any predetermined operating position, the corresponding numerals on the ags 230, 23| and 232 are visible through the aperture 33 in the escutcheon plate 34 to indicate the particular operated position of the switching unit.

The switching unit described is adapted to be incorporated in a telephone system of the character of that disclosed and claimed in the copending application of Clarence E. Lomax, Serial No. 214,724, iiled June 20, 1938; and to this end the switching unit is provided with suitable arrangements adapted to be utilized in indicating and controlling certain operations thereof. More specifically, the switching unit is provided with a pair of contact sets 233 and 280 mounted on a bracket 234 secured by screws 234B to the base plate 28. 'I'he contact set 233 comprises a pair of cooperating flexible contact springs 235 and 236 biased into engagement and adapted to be moved into disengagement by an insulating button |46a carried by the armature |46 of the operating motor MI, the button |46a being adapted to engage an extended portion of the contact spring 236. The contact springs of the contact set 233 are moved into disengagement each time the Winding |43 of the operating motor MI is energized. By including the contact set 233 in a suitable indicating circuit, the operation of the operating motor Mi may be readily registered.

The contact set 280 comprises a pair of cooperating iiexible contact springs 28| and 282 biased into engagement and adapted to be moved into disengagement by an insulating button |19a carried by the arm |19 of the operating motor M2, the button |19a being adapted to engage an extended portion of the contact spring 282. 'Ihe contact springs of the contact'set 280 are moved into disengagement each time the Winding |14 of the operating motor M2 is energized. By including the contact set 280 in a suitable indicating circuit, the operation of the operating motor M2 may be readily registered.

A set of contact springs 231 is mounted on a bracket 238 secured by screws 238*3L to the base plate 28 and associated with the rack ||9 secured to the hundred bar 59. The contact set 231 comprises a pair of outside contact springs 239 and 240 and an intermediate contact spring 24|, these contact springs being normally in disengagement. The intermediate contact spring 24| carries a roller 242 on the outer end thereof which cooperates with an insulating cam plate 243 secured to the rack H9. The cam plate 243 is provided with an intermediate portion 2433, iive projections 243b extending outwardly from the intermediate portion and five depressions 243c extending inwardly from the intermediate portion. The intermediate portion 243a provided on the cam plate 243 corresponds to the normal position of the rack IIS; the ve projections 243b provided on the cam plate 243 correspond to the ve odd oil-normal positions of the rack H9; while the iive depressions 243c provided in the cam plate 243 correspond to the five even oi-normal positions of the rack H9. When the roller 242 carried on the outer end of the intermediate spring 24| engages the intermediate portion 243a of the cam plate 243, the intermediate contact spring 24| disengages the outside contact springs 239 and 240. On the other hand, when the roller 242 engages one of the projections 243| or the cam plate 243, the intermediate contact spring 24| is moved into engagement with the outside contact spring 240; and when the roller 242 engages one of the depressions 243c provided in the cam plate 243, the intermediate contact spring 24| is moved into engagement with the outside contact spring 239. Thus, when the rack ||9 occupies its normal position, the contact springs of the contact set 231 are disengaged; when the rack ||9 occupies any odd olf-normal position, the contact springs 24| and 240 are engaged; and when the rack ||9 occupies any even olf-normal position, the contact springs 24| and 239 are engaged. By including the contact set 231 in a suitable indicating circuit, the odd or even operated position of the rack ||9 and the hundred bar 59 secured thereto may be readily registered.

A contact set 245 is associated with the hundred bar 59 and the ten bar 60. 'I'he contact set 245 comprises two pairs of contact springs 241, 248 and 25|, 252, respectively, the contact springs 248 and 252 being provided with extended portions 249 and 253 respectively associated with the cam plate 243 carried by the rack HS, and a similar cam plate carried by the rack |20, the rack |20 being secured to the ten bar 60. Normally, the contact springs 241, 248 and 25|, 252 are biased into engagement and are moved into disengagement by the cam plates carried by the racks I|9 and |20. These contacts springs are so constructed and arranged that when either one of the racks ||9 or |20 is moved into an oilnormal position, both pairs of the contact springs of the contact set 245 are moved into engagement. By including the contact springs 241, 248 and 25|, 252 of the contact 245 in a suitable indicating circuit, the normal or off-normal positions of the racks ||9 and 20 and the hundred bar 59 and the ten bar 60, respectively secured thereto, may be readily registered.

Also, a jack 254 mounted on a bracket 255, secured to the base plate 28 by screws 255g, is provided, which is disposed in alignment with the opening 35 formed in the flange 29 extending along the front edge of the switching unit. The jack 254 is adapted to receive a plug inserted through the opening 35 formed in the flange 29, and is wired in a suitable testing circuit in order to provide an arrangement for testing any desired electrical condition of the switching unit.

The escapement control mechanism |54 also constitutes a sequence switch, two contact sets 260 and 210 being associated therewith. The contact set 260 comprises a pair of cooperating contact springs 26| and 262 biased into engagement, the contact spring 262 being provided with an extended portion 263 adapted to ride upon the periphery of a disc-shaped cam member 264. The cam member 264 is secured to the cam members |51, |58 and |59, and is rotatable therewith about the pin |56. Four equally spaced-apart depressions 264a are provided in the periphery of the cam member 264 which correspond to the fourth oir-normal positions of the ratchet Wheel |55. When the ratchet wheel |55 of the escapement control mechanism |54 occupies its fourth offnormal position, the extended portion 263 provided on the contact spring 262 rides into one of the depressions 264a in the periphery of the cam member 264, causing the contact springs 26| and 262 of the contact set 260 to be moved into engagement. By including the contact set 260 in a suitable indicating circuit, the fourth off-normal position of the escapement control mechanism |54 may be readily registered. The contact set 210 comprises a pair of cooperating contact springs 21| and 212 biased into disengagement, the contact spring 212 being provided with an extended portion 213 adapted to ride upon the periphery of a disc-shaped cam member 214. 'I'he cam member 214 is secured to the cam members |51, |58 and |59 and is rotatable therewith about the pin |56. Four equally spaced-apart depressions 214 are provided in the periphery of the cam member 214 which correspond to the normal or iifth off-normal positions of the ratchet wheel |55. When the ratchet wheel |55 of the escapement control mechanism |54 occupies its normal or fth oiT-normal position, the extended portion 213 provided on the Contact spring 212 rides into one of the depressions 214a in the periphery of the cam member 214, causing the contact springs 21| and 212 of the contact set 21D to be moved into` disengagement. By including the contact set 210 in a suitable indicating circuit, the normal or fth off-normal position of the escapement control mechanism |54 may be readily registered.

Referring now to the operation of the switching unit described and assuming that the switching unit is to be operated to select a particular line from the conductor bank 24, such, for example, as the fourth line in the third level or subgroup in the second group in the rst division oi lines in the conductor bank 24, it will be understood that the switching unit is controlled by a suitable impulse transmitter connected and arranged in a control circuit including the operating motors Ml, M2 and M3. In order to cause the switching unit to operate and select the line noted above; a -single energizing impulse is rst transmitted to the operating motor M2, thereby to cause the ratchet wheel |55 of the escapement control mechanism |54 to be rotated from its normal position into its first off-normal position. When the ratchet wheel 55 is rotated into its first OIT-normal position, the head |64a of the tappet |64 is moved into its striking position as previously explained, thereby conditioning the escapement Wheel |32 in the escapement mechanism to be rotated step by step in a counterclockwise direction in response to the successive energizations of the operating motor MI.

The impulsing device is then operated to transmit a rst series of impulses, comprising two impulses, thereby to cause the operating motor MI to be energized two times successively. The two successive energizations of the operating motor MI allow the escapement wheel |32 to be rotated two steps in a counterclockwise direction, thereby to cause the hundred bar '59 to be moved longitudinally toward the left from its normal position into its second olf-normal position, as previously described. This movement of the hundred bar 59 causes the iinger 64a on the lug 64 carried by the hundred bar 59 to engage the latch 66 mounted on the carriage 42 of the elementary switch 40 and to move the latch 56 into the associated slot 69 provided in the bar 10 rigidly secured by the strap 1| to the ten bar 60, as previously explained. This operation ofthe hundred bar 59 selects the elementary switch 40 to be operated, in order to select corresponding lines from the rst and second groups in the associated iirst division of lines. At the end of the first series of impulses, a single energization impulse is transmitted to the operating motor M2, thereby to cause the ratchet wheel |55 of the escapement control mechanism |54 to be rotated into its second off-normal position. When the ratchet wheel |55 is rotated into its second off-normal position, the head |65 of the tappet |65 is moved into its striking position, thereby conditioning the escapement wheel |33 in the escapement mechanism ||l to be rotated step by step in a counterclockwise direction in response to successive energizations of the operating motor MI.

The impulsing device is then operated to transmit a second series of impulses, comprising three impulses, thereby to cause the operating motor Ml to be energized three times successively. The three successive energizations of the operating motor M| allow the escapement wheel |33 to be rotated three steps in a counterclockwise direction, thereby to cause the ten bar 60 to be moved longitudinally toward the left from its normal position into its third OIT-normal position. This movement of the ten bar 60 causes the carriage 42 of the selected elementary switch 40 to be moved longitudinally toward the left from its normal position into its third oir-normal position, due to the engagement between the latch 66 and the slot 69 formed in the bar 10, which bar is rigidly secured by the strap 1| to the ten bar 60, as previously explained. This movement of the carriage 42 of the selected elementary switch 40 causes the elementary switch 40 to select the third level or subgroup in the first and second groups in the associated first division. At the end of the second series of impulses, a single energizing impulse is transmitted to the operating motor M2, thereby to cause the ratchet wheel |55 of the escapement control mechanism |54 to be rotated into its third off-normal position. When the ratchet wheel |55 is rotated into its third offnormal position, the head |66a of the tappet |66 is moved into its striking position, thereby conditioning the escapement wheel |34 in the escapement mechanism to be rotated step by step in a counterclockwise direction in response to the successive energizations of the operating motor MI.

The impulse device is then operated to transmit a third series of impulses, comprising four impulses, thereby to cause the operating motor MI to be energized four times successively. The four successive energizations of the operating motor Ml allow the escapement wheel |34 to be rotated four steps in a counterclockwise direction, thereby to cause the unit bar 6| to be moved longitudinally toward the left from its normal position into its fourth off-normal position. This movement of the unit bar 6| allows the bell crank 80 in the selected elementary switch 40 to be rotated four steps in a clockwise direction about the pivot pin 88 by the coil spring 9i?, as previously explained. This rotation of the bell crank 80 is transmitted to the under-slide 19 through the engagement between the roller 96 carried by the arm 93 of the bell crank 80 and the slot 91 in the under-slide 19, thereby to cause the under-slide 19 to be moved laterally toward the rear of the switching unit. This movement of the underslide 19 is transmitted to the slide 43 of the selected elementary switch 40 due to the engagement between the flange 86 on the under-slide 19 and the button 81 carried by the slide 43, thereby to cause the slide 43 to be moved laterally toward the rear of the switching unit from its normal position into its fourth off-normal position. When the slide 43 of the selected elementary switch 4U is moved into its fourth otfnormal position, the fourth lines in the third levels or subgroups in the first and second groups in the associated rst division are selected. The wipers 45, 46 and 41 of the rst contact set in the elementary switch 40 engage the positive, negative and control conductors, respectively, of the selected line in the first group; and the wipers 48, 49 and 50 of the second contact set in the elementary switch 40 engage the positive, negative and control conductors, respectively, of the selected line in the second group.

Thus, the elementary switch 40 is operated simultaneously to select the fourth lines in the third levels or subgroups in the rst and second groups in the associated first division of lines in the conductor bank 24 when the digits 2-3-41 are successively dialed in the order named. From the foregoing description of the operation of the switching unit, it is apparent that these same lines will be selected when the digits 1--3-4 are successively dialed in the order named, in view of the fact that the elementary switch 40 is selected to be operated when the first digit dialed is either l or 2. While corresponding lines are selected by theelementary switch 40, when either the digits 1--3--4 or 2-3--4 are dialed successively in the order named, electrical connections to these lines may be selectively established depen-ding upon whether the first digit dialed is l or 2, in View of the fact that the contact set 231 associated with the cam plate 243 secured to the rack I I9, to which the hundred bar 59 is secured, is operated to register the odd or even offnormal position of the hundred bar 59. Thus, suitable means may be included in the indicating circuit comprising the contact Set 231, which may be controlled in such a manner that electrical connections are selectively extended to the rst and second contact sets mounted on the contact controlling member 44 carried by the slide 43 of the elementary switch 40 depending upon whether the iirst digit dialed is odd or even.

At the end of the third series of impulses, a single energizing impulse is transmitted to the operating motor M2, thereby to cause the ratchet wheel |55 of the escapement control mechanism |54 to be rotated into its fourth off-normal position. When the ratchet wheel |55 is rotated into its fourth off-normal position, the head of each ofthe tappets |64, and |66 occupies its non-striking position, as previously described.

In order to interrupt the established connection to the fourth line in the third level or subgroup in the first or second group in the first division in the conductor bank 24 and to restore the switching unit to its idle position, a single energlzing impulse is transmitted to the operating motor M2 of the escapement control mechanism |54, and the operating motor M3 of the reset mechanism ||2 is energized. The single energizing impulse transmitted to the operating motor M2 causes the ratchet Wheel |55 to be rotated into its fifth off-normal position, which off-normal position of the ratchet wheel |55 constitutes a normal position thereof, thereby to condition the escapement control mechanism |54 to be responsive to a further single energizing impulse in order to initiate another operation of the switching unit, after the switching unit has been restored to its idle position. The energization of the operating motor M3 of the reset mechanism 2 causes the pin 2|| to be rotated one revolution in a counterclockwise direction, as

98 `on the fixture 99 secured to the unit bar 6| and the arm 92 on the bell crank 80. This rotation of the bell crank is transmitted to the under-slide 19 due to the engagement between the roller 96 carried by the arm 93 ofthe bell crank 80 and the slot 91 in the under-slide 19, causing the under-slide 19 to be moved laterally toward the front of the switching unit.Y

This movement of the under-slide 19 is transmitted to the slide 43 of the elementary switch 40, due to the engagement between the ange on the under-slide 19 and the button 81 carried by the slide 43, thereby to cause the contact sets carried by the slide 43 of the elementary switch 49 to disengage the fourth conductors in the third levels or subgroups in the first and second groups in the associated first division. Subsequently, the roller 220 engages the lingers |23a and |24a on the levers |23 and |24, respectively. When the finger |24a on the lever |24 is engaged, the ten bar 60 is moved longitudinally toward the right from its third off-normal position back into its normal position. This movement of the ten bar |50 causes the carriage 43 of the elementary switch 40 to be moved longitudinally toward the right from its third ofi-normal position back into its normal position, due to the engagement between the latch 66 mounted on the carriage 42 and the slot 69 formed in the bar 10 rigidly secured by the strap 1| to the ten bar 60. When the finger |23a on the lever |23 is engaged, the hundred bar 59 is moved longitudinally toward the right from its second oi -normal position back into its normal position. This movement of the hundred bar 59 causes the finger 64a on the lug |54 carried by the hundred bar 59 to disengage the latch 66 mounted on the carriage 42 of the elementary switch 46, thereby to allow the spring biased latch 66 to move out of the associated slot 69 formed in the bar 1U rigidly secured by the strap 1| to the ten bar 69. When the latch 65 mounted on the carriage 42 of the elementary switch 40 disengages the associated slot 59 formed in the bar 10, the carriage 42 of the elementary switch 40 is unlocked from the bar 19 and the elementary switch 40 is released. Thus, the switching unit is completely restored to its idle position and is again in condition to be reoperated simultaneously to select any particular lines in the odd and even groups in any one of the divisions of lines in the conductor bank 24.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made in the structure thereof, and it is contemplated in the appended claims to cover all such modifications as fall within the true spirit and Scope of the invention.

What is claimed is:

1. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a first operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common to said elementary switches for 5 Cal moving the carriage of a selected one of said elementary switches; and means including a third operating member common to said elementary switches for moving the element of said selected elementary switch.

2. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; a tlrst operating member common to said elementary switches and supported for stepby-step movement; means responsive to the stepby-step movement of said rst operating member for selecting in a predetermined order said elementary switches to be operated; a second operating member common to said elementary switches and supported for step-by-step movement; means responsive to the step-by-step movement of said second operating member for moving the carriage of a selected one of said elementary switches step by step in said ilrst direction; a third operating member common to said elementary switches and supported for stepby-step movement; and means responsive to the step-by-step movement of said third operating member for moving the element of said selected elementary switch step by step in said second direction.

3. An automatic switching unit comprising a plurality of elementary switches; each of said, elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a first operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including a third operating member common to said elementary switches for moving the element of said selected elementary switch; and means for moving successively said first, second, and third operating members.

4. An automatic switching unit comprising a plurality of elementary switches; each oi said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a rst operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common te said elementary switches for moving the carriage of a selected one of said elementary switches; means including a third operating member common to said elementary switches for moving the element of said selected elementary switch; means for moving said operating members; and means including an escapement mechanism for controlling selectively the movements of said operating members.

5. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; means including an operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including another operating member common to said elementary switches for moving the element of said selected elementary switch; means for moving said operating members; and means lncluding an escapement mechanism for controlling selectively the movements of said operating members.

6. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a iirst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; means including an operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including another operating member common to said elementary switches for moving the element of said selected elementary switch; means for moving said operating members; an escapement member individually associated with each of said operating members and operative to control the movement of the associated operating member; and means for operating said escapement members selectively.

'1. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; an operating member common to said elementary switches and supported for step-by-step movement; means responsive to the step-by-step movement of said operating member for moving the carriage of a selected one of said elementary switches step by step in said first direction; another operating member common to said elementary switches and supported for step-by-step movement; means responsive to the step-by-step movement of said other operating member for moving the element of said selected elementary switch step by step in said second direction; a normally inoperative escapement member individually associated with each of said operating members and operative to control the step-by-step movement of the associated operating member; means for rendering said escapement members operative selectively; and means for repeatedly operating an operative one of said escapement members.

8. An automatic switching unit comprising a plurality of elementary switches; each of said switches including a movable carriage having a normal position and a plurality of off-normal positions, a movable element carried by said carriage and having a normal position and a plurality of oir-normal positions, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; two movable operating members common to said elementary switches, each of said operating members having a normal position and a plurality of off-normal positions and being biased away from its normal position; means for selecting in a predetermined order said operating members to be moved; means including an escapement mechanism for controlling selectively the oiT-normal position to which a selected one of said operating members is moved; means for causing the carriage of a selected one of said elementary switches to be moved to an off-normal position corresponding to the ori-normal position of one of said operating members; and means for causing the element of said selected elementary switch to be moved to an oil-normal position corresponding to the off-normal position of the other of said operating members.

9. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a longitudinally movable carriage having a normal position and a plurality of off-normal positions; a laterally movable element carried by said carriage and having a normal position and a plurality of olnormal positions, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; two operating members common to said elementary switches and supported for longitudinal movements, each of said operating members having a normal position and a plurality of ofinormal positions and being biased away from its normal position; means for selecting in a predetermined order said operating members to be moved; means including an escapement mechanism for controlling selectively the oil-normal position to which a selected one oi' said operating members is moved; means for causing the carriage of a selected one of said elementary switches to be moved longitudinally to an olinormal position corresponding to the off-normal position of one of said operating members; and means for causing the element of said selected elementary switch to be moved laterally to an off-normal position corresponding to the oil-normal position of the other of said operating members.

10. An automatic switching unit comprising a plurality of elementary switches; each of said switches including a movable carriage having a normal position and a plurality of ofi-normal positions, a movable element carried by said carriage and having a normal position and a plurality of oil-normal positions, and a contact controlling member carried by said element; means for selecting any one of said elementary switches to be operated; two operating members common to said elementary switches, each of said operating members having a normal position and a plurality of off-normal positions and being biased away from its normal position; means including an escapement mechanism individually associated with each of said operating members for controlling the movement of the associated operating member away from its normal position; a striking member associated with said escapement mechanism; tappets individually associated with said escapement mechanisms and commonly associated with said striking member, each of said tappets being operative to transmit blows from said striking member to the associated escapement mechanism; means for operating selectively said tappets; means for actuating repeatedly said striking member, thereby to cause the escapement mechanism individually associated with an operated one of said tappets to control the movement of the associated operating member into an ofi-normal position corresponding to the number of actuations of said striking member; means for causing the carriage of a selected One of Said elementary switches to be moved to an off-normal position corresponding to the orf-normal position of one of said operating members; and means for causing the element of said selected elementary switch to be moved to an off-normal position corresponding to the off-normal position of the other of said operating members.

11. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; first and second movable operating members common to said elementary switches; means responsive to the movement of said first operating member for locking selectively the carriages of said elementary switches to said second operating member, thereby to cause the carriage of a selected one of said elementary switches to be locked to said second operating member for movement with said second operating member; and means for moving the element of said selected elementary switch.

12. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; first and second movable operating members common to said elementary switches; means responsive to the movement of said rst operating member for locking selectively the carriages of said elementary switches to said second operating member, thereby to cause the carriage of a selected one of said elementary switches to be locked to said second operating member for movement with said second operating member; means for moving said first operating member; means including an escapement mechanism for controlling the movement of said first operating member; and means for moving the element of said selected elementary switch.

13. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches being operable independently of the other of said elementary switches and including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and two movable contacts carried by said element; a bank of xed contacts associated with said switching unit and comprising a plurality of divisions each associated with a corresponding one of said elementary switches, each of said divisions of xed contacts including two groups each associated with a corresponding one of said movable contacts; means for selecting any one of said elementary switches to be operated; and means for moving the carriage and the element of a selected one of said elementary switches, thereby to cause the two movable contacts carried by the element of said selected elementary switch to engage two corresponding fixed contacts in the two groups in the associated division of xed contacts.

14. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and two movable contacts carried by said element; a bank of xed contacts associated with said switching unit and comprising a plurality of divisions each associated with a corresponding one of said elementary switches, each of said divisions of iixed contacts including two groups each associated with a corresponding one of said movable contacts; an operating member common to said elementary switches and supported for step-by-step movement; means responsive to the step-by-step movement; of said operating member for selecting in a predetermined order said elementary switches to be operated; and means for moving the carriage and the element of a selected one of said elementary switches, thereby to cause the two movable contacts carried by the element of said selected elementary switch to engage two corresponding xed contacts in the two groups in the associated division of iixed contacts.

15. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and two movable contacts carried by said element; a bank of fixed contacts associated with said switching unit and comprising a plurality of divisions each associated with a corresponding one of said elementary switches, each of said divisions of fixed contacts including two groups each associated with a corresponding one of said movable contacts; an operating member common to said elementary switches and supported for step-by-step movement; means responsive to the step-by-step movement of said operating member for selecting in a predetermined order said elementary switches to be operated; said operating member and said elementary switches being so constructed and arranged that any particular one of said elementary switches is selected to be operated when said operating member occupies two adjacent stepped positions; and means for moving the carriage and the element of a selected one of said elementary switches, thereby to cause the two movable contacts carried by the element of said selected elementary switch to engage two corresponding fixed contacts in the two groups in the associated division of fixed contacts 16. An automatic swtiching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a rst direction, an element carried by said carriage and movable in a second direction, and two movable contacts carried by said element; a bank of xed contacts associated with said switching unit and comprising a plurality of divisions each associated with a corresponding one of said elementary switches, each of said divisions of fixed contacts including two groups each associated with a corresponding one of said movable contacts; a first operating member common to said elementary switches and supported for step-by-step movement; a second operating member common to said elementary switches; means responsive to the step-by-step movement of said rst operating member for locking selectively the carriages of said elementary switches to said second operating member. thereby to cause the carriage of a selected one of said elementary switches to be locked `to said second operating member for movement with said second operating member; said first operating member and said elementary switches being so constructed and arranged that any particular one of said elementary switches is locked to said second operating member when said first operating member occupies two adjacent positions; means for moving said second operating member; and means for moving the element of said selected elementary switch, thereby to cause the two movable contacts carried by the element of said selected elementary switch to engage two corresponding fixed contacts in the two groups in the associated division of fixed contacts.

17. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a rst operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including a third operating member common to said elementary switches for moving the element of said selected elementary switch; each of said operating members having a normal position and a plurality of OIT-normal positions corresponding respectively to idle and operated positions of said switching unit; and means associated with said operating members for indicating the idle or particular operated position of said switching unit.

18. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a iirst direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a rst operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including a third operating member common to said elementary switches for moving the element of said selected elementary switch; each of said operating members having a normal position and a plurality of off-normal positions corresponding respectively to idle and operated positions of said switching unit; and means including a plurality of members individually controlled by the positions of corresponding ones of said operating members for indicating the idle or particular operated position of said switching unit.

19. An automatic switching unit comprising a plurality of elementary switches; each of said elementary switches including a carriage movable in a first direction, an element carried by said carriage and movable in a second direction, and a contact controlling member carried by said element; means including a first operating member common to said elementary switches for selecting any one of said elementary switches to be operated; means including a second operating member common to said elementary switches for moving the carriage of a selected one of said elementary switches; means including a third operating member common to said elementary switches for moving the element of said selected elementary switch; each of said operating members having a normal position and a plurality of off-normal positions corresponding respectively to idle and operated positions of said switching unit; and means including a plurality of pivotally mounted members individually connected to corresponding ones of said operating members and 

